By Somini Sengupta | Photographs and Video by Matthew Abbott
Somini Sengupta traveled to farms around New South Wales, Australia, to report this article. Updated Aug. 13, 2024
An Australian start-up is hoping fungi can pull carbon dioxide from the air and stash it underground. It’s one of several ventures trying to deploy the superpowers of soil to slow global warming.
Across 100,000 acres in the vast agricultural heartland of Australia, an unusual approach is taking root to slow down the wrecking ball of climate change. Farmers are trying to tap the superpowers of tiny subterranean tendrils of fungus to pull carbon dioxide out of the air and stash it underground.
It’s part of a big bet that entrepreneurs and investors around the world are making on whether dirt can clean up climate pollution. They are using a variety of technologies on farmland not just to grow food but to also eat the excess carbon dioxide produced by more than a century of fossil fuel burning and intensive agriculture.
Why fungus? Because fungi act as nature’s carbon traders. As they sow their crops, farmers are adding a pulverized dust of fungal spores. The fungus latches on to the crop roots, takes carbon that is absorbed by the plants from the air and locks it away in subterranean storage in a form that may keep it underground for much longer than the natural carbon cycle.
The fungal venture, the handiwork of an Australian company called Loam Bio, is among several start-ups to have mobilized hundreds of millions of dollars in investments in efforts to use soil to remove carbon dioxide from the atmosphere. Like Loam Bio, companies like Andes and Groundworks Bio Ag are also experimenting with microbes. Lithos and Mati offer farmers crushed volcanic rocks that absorb carbon to sprinkle on their fields. Silicate Carbon is milling leftover concrete into a fine powder, while several companies are scorching crop waste into charcoal.
The appeal of the Australian start-up is that it doesn’t demand too much of farmers.
“Pretty simple,” is how a fifth-generation Australian farmer named Stuart McDonald described his experience as he sowed a dusting of fungal spores with his wheat and canola seeds on his farm near Canowindra this year. “It’s not asking us to change too much. It’s not a big capital outlay.”
It’s still early days for most of these ventures, and exactly how much excess carbon they can remove and how long they can keep it underground remains contested. But their side-benefits may be equally profound. They are all aimed at restoring the health of soils that have been degraded by decades of intensive agriculture by restoring microbes and minerals that they once contained.
The carbon removal potential of soils is huge. Soils hold three times as much carbon as the atmosphere and they can potentially absorb more than 5 gigatons of carbon dioxide per year, or one-seventh of all the carbon dioxide that human activity injects into the atmosphere, according to the Intergovernmental Panel on Climate Change. That makes them the world’s second-largest carbon store, after oceans.
“I think soils will play a key role,” said Rob Jackson, a climate scientist at Stanford University, though he was skeptical about whether the promise of the fungal additives in field tests could have a statistically significant effect on working farms.
“We would need to touch billions of acres to make a real difference,” he said.
Not to mention, agriculture itself creates a climate problem, accounting for a fourth of the world’s greenhouse gas emissions.
Loam Bio’s fungal talcum has been spread on 100,000 acres in Australia this year, with 250,000 acres expected to come online next year. A half-dozen farmers in the United States are trying the product on their soy fields. Field tests are underway in Canada and Brazil.
Loam Bio has attracted $100 million in investments so far, making it among the most well-funded of the many start-ups looking for ways to store more carbon in the dirt.
Critics are concerned that the new technologies treat the symptom and not the cause of climate change. They “can’t be used as an excuse to continue burning fossil fuels,” Dr. Jackson said.
Loam Bio’s co-founder and a sixth-generation farmer, Tegan Nock, agreed.
“This is just one of the things that can buy us time,” she said.
Why Australia?
Not all farmers are doing this out of altruism.
More carbon means better soil health and better yields. But in Australia, farmers have another motive. They hope to reap a harvest of government-issued credits if they can demonstrate they have stored carbon underground.
This is not the first time that farmers in the area have tried to cash in on soil carbon.
Once, Mr. McDonald, 52, trucked in solid waste from Sydney’s sewage to fertilize his fields and measured a small uptick in soil carbon. But he has no idea how long it lasted. Some farmers planted trees on a portion of their land and soil carbon increased for a few years, then flattened out.
Critics said carbon credits were awarded not for substantial changes but for seasonal fluctuations in weather: In unusually wet years, carbon accrued in the soil, only to dissipate in dry years. One study warned that the number of carbon credits issued for farming projects was inflated.
Accounting for carbon in soil is complicated by the fact that it comes in different forms. Most soil carbon is in the form of highly volatile organic matter. On farmland, that would be plant residue or manure. It can return to the atmosphere in a matter of years, or a drought or fire can burn it up even faster, releasing carbon dioxide back into the air.
But there are more stable types of soil carbon, including one that attaches itself to minerals in the dirt and remains there for a century or more. Loam Bio says that its fungal spores can help build that more stable soil carbon. They measure it for their farmer customers, using one-meter-deep soil cores.
Fungi do the vital work underground. They take the carbon dioxide that plants pull from the air during photosynthesis, stash it underground, and give back nutrients that plants need.
To Alan Richardson, a soil biologist at the Commonwealth Scientific and Industrial Research Organization, a government agency in Australia, the concept of using fungi to store carbon underground makes sense. But it would work only if farmers applied the fungi year after year, allowing the soil to build carbon over many years.
“The fundamental principle behind it is sound, but whether it translates into practice we don’t know,” he said.
Still, Steve Nicholson, a farmer near the town of Forbes, is so bullish on the prospect that he signed a 25-year contract with Loam. “It’s a gamble,” he said. “But it’s a very, very good gamble.”
Loam’s technicians measured his base-line soil carbon in February, at the peak of the hot, dry season. They will be back to find out whether his soil carbon has increased next February, and to determine how much of it is in the more stable forms.
Ms. Nock, the co-founder of Loam Bio, tells her customers they can expect to store one to two tons of stable carbon in every hectare, or 2.4 acres.
Australia’s government-run carbon credit agency will have to verify how much carbon he has added before issuing any credits. Mr. Nicholson hopes to cash in by next July.
His earnings will depend on Australia’s carbon price at that time. He is eyeing more than 100 Australian dollars, or about $65, per hectare. (Click here to read the entire article from the New York Times.)
Comments